Area Forecast Discussion
Issued by NWS Salt Lake City, UT
FXUS65 KSLC 252226
Area Forecast Discussion
National Weather Service Salt Lake City UT
326 PM MST Sat Feb 25 2017
.SYNOPSIS...A weak weather will cross the area tonight. A
stronger storm is on tap for the first part of next week.
.SHORT TERM (THROUGH 12Z TUESDAY)...
Water Vapor Satellite shows a positively tilted trough across the
Northern Rockies to a strong closed circulation off the Northern
California coast. 400-200mb MDCARS wind observations place a
125-155kt westerly jet from California across the Plains.
GOES/SLC 12Z RAOB/HRRR indicate that precipitable water values
vary from 0.05"-0.10" mountains to 0.15"-0.20" valleys.
The current storm system is cold yet lacking with moisture. This
is why as the positively tilted trough crosses the region into
tomorrow, the models are not producing a lot of precipitation.
The cold pool aloft crosses from north to south over the state
through the weekend. It will be cold enough that even a little
snow could cause travel difficulties especially tonight into
tomorrow across central and south central Utah.
The next storm will approach on the same track late tomorrow
night...impacting the area Monday. Since its taking a similar
track this system does not have a lot of moisture either.
However, this one brings better dynamics especially height falls
and jet. Therefore expecting more precipitation.
The cold front eases across the West Desert Sunday night, reaching
Salt Lake between 09z-12z Monday. This boundary slowly makes its
way into central Utah midday Monday, settling across southern Utah
Monday night. As the boundary crosses the state, it tightens up
which should produce the heavier snow totals south of Interstate
80. Snow will start earlier than one would expect ahead of the
cold front across southwest Utah thanks to the arrival of the left
exit region of an upper level jet.
Road surfaces will be cold Sunday night. This will likely cause
travel problems Monday, beginning with the Monday morning commute
as the snow moves into the region, transitioning to central and
south central Utah Monday night.
.LONG TERM (AFTER 12Z TUESDAY)...
The final cold trough in this northwest flow aloft will move
across the area Tuesday. The thermal dynamics at 500mb look decent
by both the GFS and EC but the 700mb and below dynamics are
rather weak in addition to a lack of deep moisture as this feature
has moved down across a land trajectory from western Canada.
Therefore have lowered the PoPs for Tuesday. Cold temperatures
will accompany this system and with mostly cloudy skies and
scattered snow showers over western Utah have lowered the temps a
couple from the previous forecast for Tuesday. The southeast
portion of the CWA has the best chance for some scattered snow
showers Tuesday afternoon as the dynamics aloft will be the
The EC and GFS are in locked step Wednesday and Thursday with the
ridge building over the CWA. After Thursday the operational GFS
becomes more of an outlier compared to the GFS ensemble which
remains in good agreement with the EC. Consequently have gone with
the EC through Saturday. The EC and GFS ensemble keep a flat ridge
in place over the CWA which prevents the trough that the GFS from
reaching the northern portions of the CWA. Have backed off on the
low PoPs across the north and kept the rest of the CWA dry.
Temperatures will be on the warming trend from Wednesday forward
with the faster response occurring in the mountains as an inversion
will slow the warming in the valleys. Temperatures will be near
normal by Thursday and then go above normal Friday and Saturday.
Light snow showers are expected to gradually diminish through
22Z. Much drier air has moved into the area and this should keep
ceilings at or above 6500 feet AGL, improving further after 00Z.
Northwesterly winds are expected to transition to southerly winds
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